DULUTH, Minn. (AP) – Students who own season tickets to Minnesota-Duluth’s men’s hockey games are being warned to shape up after reports of racist chants during recent games against the North Dakota Fighting Sioux.

Athletic Director Bob Nielson sent students a letter warning that inappropriate comments directed at officials or other teams could get them tossed from the arena, or cost them their tickets.

The Duluth News-Tribune reports (http://bit.ly/AaEhLv ) students began chanting “smallpox blankets” and other phases at the North Dakota mascot during the Feb. 10-11 series.

North Dakota has resumed using the Fighting Sioux nickname despite threats from the NCAA that it would harm the school’s chances at hosting postseason events.

Duluth is in the midst of an anti-racism campaign. Billboards and posters throughout the city are aiming to create dialogue about racism.